This application relates to a type of fire suppressor wherein a liquid suppressor agent is driven out of a canister by the formation of gas bubbles.
Fire suppressors are known, and include a variety of agents that are discharged toward a fire. One type of high discharge rate fire suppressor uses rapid desorption of a pressurizing agent, which is typically pressurized nitrogen or carbon dioxide, from a volatile liquid agent, to drive the liquid agent out of the suppressor canister.
Typically, a valve is triggered to open, and bubbles of a dissolved gas rapidly form in the agent creating a foaming mixture that expands and discharges from the suppressor canister. The formation of this foam is of critical importance to the effective deployment of the agent.
Recent studies of the phenomenon have indicated that the proportion of agent discharged decreases as the temperature decreases. This is believed to be due to a combination of thermodynamic and kinetic effects. Some gases become less soluble in the liquid agent at low temperatures, but also the rate of bubble formation will change.
In order to grow, the bubbles must overcome a pressure inside the suppressor and also the resistance caused by the surface tension of the liquid, which increases at low temperature. Tests have suggested that the initial formation of bubbles may be the rate-determining step at these low temperatures, particularly for a highly soluble gas.
It is known to provide nucleation sites on a surface to form gas bubbles. One example of a nucleation site is the inclusion of surface imperfections on champagne flutes. Such a site can provide a surface where gas molecules can agglomerate.
However, nucleation sites have not been utilized in fire suppression cylinders.